The present invention relates to a data scrambler for scrambling and transmitting a transmit data bit sequence. The invention also relates to a data descrambler for use in combination with a data scrambler.
In a data transmission system, if bits of the same symbol (bit zeros or ones) come out consecutively in a transmit data bit sequence, no timing signals can be extracted on the receive side from the transmit data. By the prior art, therefore, the transmit data bit sequence is scrambled with a self-timing scrambler to prevent the consecutive appearance of the same symbols in the bit sequence on the transmission path.
The conventional data scrambler referred to above involves the problem that, when starting the transmission of data for instance, the same symbols will consecutively come out after scrambling if the bit sequence in the register of the scrambler is wholly the same as that to be inputted to the scrambler.